This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The primary objective is to establish the pharmacokinetic profile at steady state of nevirapine XR in children from e3 to 18 years of age. Adherence is a major factor in determining the degree of viral suppression achieved in response to antiretroviral therapy. An extended release formulation of nevirapine may offer a meaningful therapeutic benefit, relative to marketed nevirapine oral suspension and 200 mg BID tablets by facilitating a once daily dosing regimen, thus improving treatment compliance. In addition, nevirapine extended release could demonstrate improved tolerability in comparison with the marketed suspension.